jtag adjustments

  . include openocd amdm37x.cfg
    with full u-boot spl mlo trace in reset-init hook.
    most likely this only needs 100 lines but i'm starting with the full trace

  . disable caching & paging changes for now - this seems to hang (or just take
    too logn?) once executed from the bare environment, probably something subtly
    wrong with the init code.